So looking at the specs for these do you think it will be ok to power via 5V GPIO pin? or will it maybe create too much noise and upset the RPi?
The reason that I ask is if it is ok to power from GPIO pin then this linear will be a nice plug and play
Without testing with the linear actuators you want to use, I wouldn’t guarantee that the 5v rail won’t be too noisy for the Raspberry Pi. The PivotPi (and the PivotPi Base Kit) comes with a 4xAA battery holder; I would recommend using that for powering servos (or linear actuators in your case).
I am always fighting for space on my robots especially as they become more complex. These linear acuators had the big advantage was physical size as well as performance. If I have to add another battery to power them it defeats the purpose of spending the money to buy them.
I have just noticed that they make a lego model https://www.actuonix.com/lego-actuators-s/1929.htm but I will have to email them if it will handle the higher voltage of the BrickPi.
If I am willing to spend big money there is these beauties https://www.actuonix.com/P16-P-Linear-Actuator-p/p16-p-.htm that have crazy impressive specs and run on 12v which should power in parallel off my main battery.
It looks like those Lego compatible ones can be run directly from a motor port of the BrickPi, as if they were standard Lego motors. They would simplify the design, and minimize space required.